SLC6A4 and depressive disorder: Notably, depressive disorders are associated with decreased levels of 5-HT, its transporter (5-HTT), DA, and norepinephrine (NE), alongside the elevated expression of inflammatory and cell-death markers such as GSDMD, NF-κB p65, Interleukin (IL)-1β, IL-6, and Tumor Necrosis Factor (TNF)-α, which are common targets of antidepressant therapies [41,42,43,44].